<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    姓：<input type="text" v-model="firstName"><br>
    名：<input type="text" v-model="lastName"><br>
    <p>姓名：{{fullName}}</p>
    <button @click="changeName()">修改姓名</button>
  </div>
  <script src="./vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        firstName: '刘',
        lastName: '备',
      },
      methods: {
        changeName() {
          this.fullName = '吕小布'
        }
      }
      ,
      computed: {
      // 简写 → 获取
    //   fullName() {
    //     return this.firstName + this.lastName
    // } 

    // 完成写法 → 获取 + 设置
    fullName: {
      // （1）当fullName计算属性，被获取求值时，执行get（有缓存，优先读取缓存）
      get() {
        return this.firstName + this.lastName
      },
      set(value) {
        console.log(value)
        this.firstName = value.slice(0, 1)
        this.lastName = value.slice(1)
      }
    }
      }
    })
  </script>
</body>
</html>